jaroslav@557: /*
jaroslav@557:  * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
jaroslav@557:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
jaroslav@557:  *
jaroslav@557:  * This code is free software; you can redistribute it and/or modify it
jaroslav@557:  * under the terms of the GNU General Public License version 2 only, as
jaroslav@557:  * published by the Free Software Foundation.  Oracle designates this
jaroslav@557:  * particular file as subject to the "Classpath" exception as provided
jaroslav@557:  * by Oracle in the LICENSE file that accompanied this code.
jaroslav@557:  *
jaroslav@557:  * This code is distributed in the hope that it will be useful, but WITHOUT
jaroslav@557:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
jaroslav@557:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
jaroslav@557:  * version 2 for more details (a copy is included in the LICENSE file that
jaroslav@557:  * accompanied this code).
jaroslav@557:  *
jaroslav@557:  * You should have received a copy of the GNU General Public License version
jaroslav@557:  * 2 along with this work; if not, write to the Free Software Foundation,
jaroslav@557:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
jaroslav@557:  *
jaroslav@557:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
jaroslav@557:  * or visit www.oracle.com if you need additional information or have any
jaroslav@557:  * questions.
jaroslav@557:  */
jaroslav@557: 
jaroslav@557: package java.util;
jaroslav@557: 
jaroslav@557: /**
jaroslav@557:  * This class provides a skeletal implementation of the {@link List}
jaroslav@557:  * interface to minimize the effort required to implement this interface
jaroslav@557:  * backed by a "random access" data store (such as an array).  For sequential
jaroslav@557:  * access data (such as a linked list), {@link AbstractSequentialList} should
jaroslav@557:  * be used in preference to this class.
jaroslav@557:  *
jaroslav@557:  * <p>To implement an unmodifiable list, the programmer needs only to extend
jaroslav@557:  * this class and provide implementations for the {@link #get(int)} and
jaroslav@557:  * {@link List#size() size()} methods.
jaroslav@557:  *
jaroslav@557:  * <p>To implement a modifiable list, the programmer must additionally
jaroslav@557:  * override the {@link #set(int, Object) set(int, E)} method (which otherwise
jaroslav@557:  * throws an {@code UnsupportedOperationException}).  If the list is
jaroslav@557:  * variable-size the programmer must additionally override the
jaroslav@557:  * {@link #add(int, Object) add(int, E)} and {@link #remove(int)} methods.
jaroslav@557:  *
jaroslav@557:  * <p>The programmer should generally provide a void (no argument) and collection
jaroslav@557:  * constructor, as per the recommendation in the {@link Collection} interface
jaroslav@557:  * specification.
jaroslav@557:  *
jaroslav@557:  * <p>Unlike the other abstract collection implementations, the programmer does
jaroslav@557:  * <i>not</i> have to provide an iterator implementation; the iterator and
jaroslav@557:  * list iterator are implemented by this class, on top of the "random access"
jaroslav@557:  * methods:
jaroslav@557:  * {@link #get(int)},
jaroslav@557:  * {@link #set(int, Object) set(int, E)},
jaroslav@557:  * {@link #add(int, Object) add(int, E)} and
jaroslav@557:  * {@link #remove(int)}.
jaroslav@557:  *
jaroslav@557:  * <p>The documentation for each non-abstract method in this class describes its
jaroslav@557:  * implementation in detail.  Each of these methods may be overridden if the
jaroslav@557:  * collection being implemented admits a more efficient implementation.
jaroslav@557:  *
jaroslav@557:  * <p>This class is a member of the
jaroslav@557:  * <a href="{@docRoot}/../technotes/guides/collections/index.html">
jaroslav@557:  * Java Collections Framework</a>.
jaroslav@557:  *
jaroslav@557:  * @author  Josh Bloch
jaroslav@557:  * @author  Neal Gafter
jaroslav@557:  * @since 1.2
jaroslav@557:  */
jaroslav@557: 
jaroslav@557: public abstract class AbstractList<E> extends AbstractCollection<E> implements List<E> {
jaroslav@557:     /**
jaroslav@557:      * Sole constructor.  (For invocation by subclass constructors, typically
jaroslav@557:      * implicit.)
jaroslav@557:      */
jaroslav@557:     protected AbstractList() {
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * Appends the specified element to the end of this list (optional
jaroslav@557:      * operation).
jaroslav@557:      *
jaroslav@557:      * <p>Lists that support this operation may place limitations on what
jaroslav@557:      * elements may be added to this list.  In particular, some
jaroslav@557:      * lists will refuse to add null elements, and others will impose
jaroslav@557:      * restrictions on the type of elements that may be added.  List
jaroslav@557:      * classes should clearly specify in their documentation any restrictions
jaroslav@557:      * on what elements may be added.
jaroslav@557:      *
jaroslav@557:      * <p>This implementation calls {@code add(size(), e)}.
jaroslav@557:      *
jaroslav@557:      * <p>Note that this implementation throws an
jaroslav@557:      * {@code UnsupportedOperationException} unless
jaroslav@557:      * {@link #add(int, Object) add(int, E)} is overridden.
jaroslav@557:      *
jaroslav@557:      * @param e element to be appended to this list
jaroslav@557:      * @return {@code true} (as specified by {@link Collection#add})
jaroslav@557:      * @throws UnsupportedOperationException if the {@code add} operation
jaroslav@557:      *         is not supported by this list
jaroslav@557:      * @throws ClassCastException if the class of the specified element
jaroslav@557:      *         prevents it from being added to this list
jaroslav@557:      * @throws NullPointerException if the specified element is null and this
jaroslav@557:      *         list does not permit null elements
jaroslav@557:      * @throws IllegalArgumentException if some property of this element
jaroslav@557:      *         prevents it from being added to this list
jaroslav@557:      */
jaroslav@557:     public boolean add(E e) {
jaroslav@557:         add(size(), e);
jaroslav@557:         return true;
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * {@inheritDoc}
jaroslav@557:      *
jaroslav@557:      * @throws IndexOutOfBoundsException {@inheritDoc}
jaroslav@557:      */
jaroslav@557:     abstract public E get(int index);
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * {@inheritDoc}
jaroslav@557:      *
jaroslav@557:      * <p>This implementation always throws an
jaroslav@557:      * {@code UnsupportedOperationException}.
jaroslav@557:      *
jaroslav@557:      * @throws UnsupportedOperationException {@inheritDoc}
jaroslav@557:      * @throws ClassCastException            {@inheritDoc}
jaroslav@557:      * @throws NullPointerException          {@inheritDoc}
jaroslav@557:      * @throws IllegalArgumentException      {@inheritDoc}
jaroslav@557:      * @throws IndexOutOfBoundsException     {@inheritDoc}
jaroslav@557:      */
jaroslav@557:     public E set(int index, E element) {
jaroslav@557:         throw new UnsupportedOperationException();
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * {@inheritDoc}
jaroslav@557:      *
jaroslav@557:      * <p>This implementation always throws an
jaroslav@557:      * {@code UnsupportedOperationException}.
jaroslav@557:      *
jaroslav@557:      * @throws UnsupportedOperationException {@inheritDoc}
jaroslav@557:      * @throws ClassCastException            {@inheritDoc}
jaroslav@557:      * @throws NullPointerException          {@inheritDoc}
jaroslav@557:      * @throws IllegalArgumentException      {@inheritDoc}
jaroslav@557:      * @throws IndexOutOfBoundsException     {@inheritDoc}
jaroslav@557:      */
jaroslav@557:     public void add(int index, E element) {
jaroslav@557:         throw new UnsupportedOperationException();
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * {@inheritDoc}
jaroslav@557:      *
jaroslav@557:      * <p>This implementation always throws an
jaroslav@557:      * {@code UnsupportedOperationException}.
jaroslav@557:      *
jaroslav@557:      * @throws UnsupportedOperationException {@inheritDoc}
jaroslav@557:      * @throws IndexOutOfBoundsException     {@inheritDoc}
jaroslav@557:      */
jaroslav@557:     public E remove(int index) {
jaroslav@557:         throw new UnsupportedOperationException();
jaroslav@557:     }
jaroslav@557: 
jaroslav@557: 
jaroslav@557:     // Search Operations
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * {@inheritDoc}
jaroslav@557:      *
jaroslav@557:      * <p>This implementation first gets a list iterator (with
jaroslav@557:      * {@code listIterator()}).  Then, it iterates over the list until the
jaroslav@557:      * specified element is found or the end of the list is reached.
jaroslav@557:      *
jaroslav@557:      * @throws ClassCastException   {@inheritDoc}
jaroslav@557:      * @throws NullPointerException {@inheritDoc}
jaroslav@557:      */
jaroslav@557:     public int indexOf(Object o) {
jaroslav@557:         ListIterator<E> it = listIterator();
jaroslav@557:         if (o==null) {
jaroslav@557:             while (it.hasNext())
jaroslav@557:                 if (it.next()==null)
jaroslav@557:                     return it.previousIndex();
jaroslav@557:         } else {
jaroslav@557:             while (it.hasNext())
jaroslav@557:                 if (o.equals(it.next()))
jaroslav@557:                     return it.previousIndex();
jaroslav@557:         }
jaroslav@557:         return -1;
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * {@inheritDoc}
jaroslav@557:      *
jaroslav@557:      * <p>This implementation first gets a list iterator that points to the end
jaroslav@557:      * of the list (with {@code listIterator(size())}).  Then, it iterates
jaroslav@557:      * backwards over the list until the specified element is found, or the
jaroslav@557:      * beginning of the list is reached.
jaroslav@557:      *
jaroslav@557:      * @throws ClassCastException   {@inheritDoc}
jaroslav@557:      * @throws NullPointerException {@inheritDoc}
jaroslav@557:      */
jaroslav@557:     public int lastIndexOf(Object o) {
jaroslav@557:         ListIterator<E> it = listIterator(size());
jaroslav@557:         if (o==null) {
jaroslav@557:             while (it.hasPrevious())
jaroslav@557:                 if (it.previous()==null)
jaroslav@557:                     return it.nextIndex();
jaroslav@557:         } else {
jaroslav@557:             while (it.hasPrevious())
jaroslav@557:                 if (o.equals(it.previous()))
jaroslav@557:                     return it.nextIndex();
jaroslav@557:         }
jaroslav@557:         return -1;
jaroslav@557:     }
jaroslav@557: 
jaroslav@557: 
jaroslav@557:     // Bulk Operations
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * Removes all of the elements from this list (optional operation).
jaroslav@557:      * The list will be empty after this call returns.
jaroslav@557:      *
jaroslav@557:      * <p>This implementation calls {@code removeRange(0, size())}.
jaroslav@557:      *
jaroslav@557:      * <p>Note that this implementation throws an
jaroslav@557:      * {@code UnsupportedOperationException} unless {@code remove(int
jaroslav@557:      * index)} or {@code removeRange(int fromIndex, int toIndex)} is
jaroslav@557:      * overridden.
jaroslav@557:      *
jaroslav@557:      * @throws UnsupportedOperationException if the {@code clear} operation
jaroslav@557:      *         is not supported by this list
jaroslav@557:      */
jaroslav@557:     public void clear() {
jaroslav@557:         removeRange(0, size());
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * {@inheritDoc}
jaroslav@557:      *
jaroslav@557:      * <p>This implementation gets an iterator over the specified collection
jaroslav@557:      * and iterates over it, inserting the elements obtained from the
jaroslav@557:      * iterator into this list at the appropriate position, one at a time,
jaroslav@557:      * using {@code add(int, E)}.
jaroslav@557:      * Many implementations will override this method for efficiency.
jaroslav@557:      *
jaroslav@557:      * <p>Note that this implementation throws an
jaroslav@557:      * {@code UnsupportedOperationException} unless
jaroslav@557:      * {@link #add(int, Object) add(int, E)} is overridden.
jaroslav@557:      *
jaroslav@557:      * @throws UnsupportedOperationException {@inheritDoc}
jaroslav@557:      * @throws ClassCastException            {@inheritDoc}
jaroslav@557:      * @throws NullPointerException          {@inheritDoc}
jaroslav@557:      * @throws IllegalArgumentException      {@inheritDoc}
jaroslav@557:      * @throws IndexOutOfBoundsException     {@inheritDoc}
jaroslav@557:      */
jaroslav@557:     public boolean addAll(int index, Collection<? extends E> c) {
jaroslav@557:         rangeCheckForAdd(index);
jaroslav@557:         boolean modified = false;
jaroslav@557:         for (E e : c) {
jaroslav@557:             add(index++, e);
jaroslav@557:             modified = true;
jaroslav@557:         }
jaroslav@557:         return modified;
jaroslav@557:     }
jaroslav@557: 
jaroslav@557: 
jaroslav@557:     // Iterators
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * Returns an iterator over the elements in this list in proper sequence.
jaroslav@557:      *
jaroslav@557:      * <p>This implementation returns a straightforward implementation of the
jaroslav@557:      * iterator interface, relying on the backing list's {@code size()},
jaroslav@557:      * {@code get(int)}, and {@code remove(int)} methods.
jaroslav@557:      *
jaroslav@557:      * <p>Note that the iterator returned by this method will throw an
jaroslav@557:      * {@link UnsupportedOperationException} in response to its
jaroslav@557:      * {@code remove} method unless the list's {@code remove(int)} method is
jaroslav@557:      * overridden.
jaroslav@557:      *
jaroslav@557:      * <p>This implementation can be made to throw runtime exceptions in the
jaroslav@557:      * face of concurrent modification, as described in the specification
jaroslav@557:      * for the (protected) {@link #modCount} field.
jaroslav@557:      *
jaroslav@557:      * @return an iterator over the elements in this list in proper sequence
jaroslav@557:      */
jaroslav@557:     public Iterator<E> iterator() {
jaroslav@557:         return new Itr();
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * {@inheritDoc}
jaroslav@557:      *
jaroslav@557:      * <p>This implementation returns {@code listIterator(0)}.
jaroslav@557:      *
jaroslav@557:      * @see #listIterator(int)
jaroslav@557:      */
jaroslav@557:     public ListIterator<E> listIterator() {
jaroslav@557:         return listIterator(0);
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * {@inheritDoc}
jaroslav@557:      *
jaroslav@557:      * <p>This implementation returns a straightforward implementation of the
jaroslav@557:      * {@code ListIterator} interface that extends the implementation of the
jaroslav@557:      * {@code Iterator} interface returned by the {@code iterator()} method.
jaroslav@557:      * The {@code ListIterator} implementation relies on the backing list's
jaroslav@557:      * {@code get(int)}, {@code set(int, E)}, {@code add(int, E)}
jaroslav@557:      * and {@code remove(int)} methods.
jaroslav@557:      *
jaroslav@557:      * <p>Note that the list iterator returned by this implementation will
jaroslav@557:      * throw an {@link UnsupportedOperationException} in response to its
jaroslav@557:      * {@code remove}, {@code set} and {@code add} methods unless the
jaroslav@557:      * list's {@code remove(int)}, {@code set(int, E)}, and
jaroslav@557:      * {@code add(int, E)} methods are overridden.
jaroslav@557:      *
jaroslav@557:      * <p>This implementation can be made to throw runtime exceptions in the
jaroslav@557:      * face of concurrent modification, as described in the specification for
jaroslav@557:      * the (protected) {@link #modCount} field.
jaroslav@557:      *
jaroslav@557:      * @throws IndexOutOfBoundsException {@inheritDoc}
jaroslav@557:      */
jaroslav@557:     public ListIterator<E> listIterator(final int index) {
jaroslav@557:         rangeCheckForAdd(index);
jaroslav@557: 
jaroslav@557:         return new ListItr(index);
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     private class Itr implements Iterator<E> {
jaroslav@557:         /**
jaroslav@557:          * Index of element to be returned by subsequent call to next.
jaroslav@557:          */
jaroslav@557:         int cursor = 0;
jaroslav@557: 
jaroslav@557:         /**
jaroslav@557:          * Index of element returned by most recent call to next or
jaroslav@557:          * previous.  Reset to -1 if this element is deleted by a call
jaroslav@557:          * to remove.
jaroslav@557:          */
jaroslav@557:         int lastRet = -1;
jaroslav@557: 
jaroslav@557:         /**
jaroslav@557:          * The modCount value that the iterator believes that the backing
jaroslav@557:          * List should have.  If this expectation is violated, the iterator
jaroslav@557:          * has detected concurrent modification.
jaroslav@557:          */
jaroslav@557:         int expectedModCount = modCount;
jaroslav@557: 
jaroslav@557:         public boolean hasNext() {
jaroslav@557:             return cursor != size();
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:         public E next() {
jaroslav@557:             checkForComodification();
jaroslav@557:             try {
jaroslav@557:                 int i = cursor;
jaroslav@557:                 E next = get(i);
jaroslav@557:                 lastRet = i;
jaroslav@557:                 cursor = i + 1;
jaroslav@557:                 return next;
jaroslav@557:             } catch (IndexOutOfBoundsException e) {
jaroslav@557:                 checkForComodification();
jaroslav@557:                 throw new NoSuchElementException();
jaroslav@557:             }
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:         public void remove() {
jaroslav@557:             if (lastRet < 0)
jaroslav@557:                 throw new IllegalStateException();
jaroslav@557:             checkForComodification();
jaroslav@557: 
jaroslav@557:             try {
jaroslav@557:                 AbstractList.this.remove(lastRet);
jaroslav@557:                 if (lastRet < cursor)
jaroslav@557:                     cursor--;
jaroslav@557:                 lastRet = -1;
jaroslav@557:                 expectedModCount = modCount;
jaroslav@557:             } catch (IndexOutOfBoundsException e) {
jaroslav@557:                 throw new ConcurrentModificationException();
jaroslav@557:             }
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:         final void checkForComodification() {
jaroslav@557:             if (modCount != expectedModCount)
jaroslav@557:                 throw new ConcurrentModificationException();
jaroslav@557:         }
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     private class ListItr extends Itr implements ListIterator<E> {
jaroslav@557:         ListItr(int index) {
jaroslav@557:             cursor = index;
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:         public boolean hasPrevious() {
jaroslav@557:             return cursor != 0;
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:         public E previous() {
jaroslav@557:             checkForComodification();
jaroslav@557:             try {
jaroslav@557:                 int i = cursor - 1;
jaroslav@557:                 E previous = get(i);
jaroslav@557:                 lastRet = cursor = i;
jaroslav@557:                 return previous;
jaroslav@557:             } catch (IndexOutOfBoundsException e) {
jaroslav@557:                 checkForComodification();
jaroslav@557:                 throw new NoSuchElementException();
jaroslav@557:             }
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:         public int nextIndex() {
jaroslav@557:             return cursor;
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:         public int previousIndex() {
jaroslav@557:             return cursor-1;
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:         public void set(E e) {
jaroslav@557:             if (lastRet < 0)
jaroslav@557:                 throw new IllegalStateException();
jaroslav@557:             checkForComodification();
jaroslav@557: 
jaroslav@557:             try {
jaroslav@557:                 AbstractList.this.set(lastRet, e);
jaroslav@557:                 expectedModCount = modCount;
jaroslav@557:             } catch (IndexOutOfBoundsException ex) {
jaroslav@557:                 throw new ConcurrentModificationException();
jaroslav@557:             }
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:         public void add(E e) {
jaroslav@557:             checkForComodification();
jaroslav@557: 
jaroslav@557:             try {
jaroslav@557:                 int i = cursor;
jaroslav@557:                 AbstractList.this.add(i, e);
jaroslav@557:                 lastRet = -1;
jaroslav@557:                 cursor = i + 1;
jaroslav@557:                 expectedModCount = modCount;
jaroslav@557:             } catch (IndexOutOfBoundsException ex) {
jaroslav@557:                 throw new ConcurrentModificationException();
jaroslav@557:             }
jaroslav@557:         }
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * {@inheritDoc}
jaroslav@557:      *
jaroslav@557:      * <p>This implementation returns a list that subclasses
jaroslav@557:      * {@code AbstractList}.  The subclass stores, in private fields, the
jaroslav@557:      * offset of the subList within the backing list, the size of the subList
jaroslav@557:      * (which can change over its lifetime), and the expected
jaroslav@557:      * {@code modCount} value of the backing list.  There are two variants
jaroslav@557:      * of the subclass, one of which implements {@code RandomAccess}.
jaroslav@557:      * If this list implements {@code RandomAccess} the returned list will
jaroslav@557:      * be an instance of the subclass that implements {@code RandomAccess}.
jaroslav@557:      *
jaroslav@557:      * <p>The subclass's {@code set(int, E)}, {@code get(int)},
jaroslav@557:      * {@code add(int, E)}, {@code remove(int)}, {@code addAll(int,
jaroslav@557:      * Collection)} and {@code removeRange(int, int)} methods all
jaroslav@557:      * delegate to the corresponding methods on the backing abstract list,
jaroslav@557:      * after bounds-checking the index and adjusting for the offset.  The
jaroslav@557:      * {@code addAll(Collection c)} method merely returns {@code addAll(size,
jaroslav@557:      * c)}.
jaroslav@557:      *
jaroslav@557:      * <p>The {@code listIterator(int)} method returns a "wrapper object"
jaroslav@557:      * over a list iterator on the backing list, which is created with the
jaroslav@557:      * corresponding method on the backing list.  The {@code iterator} method
jaroslav@557:      * merely returns {@code listIterator()}, and the {@code size} method
jaroslav@557:      * merely returns the subclass's {@code size} field.
jaroslav@557:      *
jaroslav@557:      * <p>All methods first check to see if the actual {@code modCount} of
jaroslav@557:      * the backing list is equal to its expected value, and throw a
jaroslav@557:      * {@code ConcurrentModificationException} if it is not.
jaroslav@557:      *
jaroslav@557:      * @throws IndexOutOfBoundsException if an endpoint index value is out of range
jaroslav@557:      *         {@code (fromIndex < 0 || toIndex > size)}
jaroslav@557:      * @throws IllegalArgumentException if the endpoint indices are out of order
jaroslav@557:      *         {@code (fromIndex > toIndex)}
jaroslav@557:      */
jaroslav@557:     public List<E> subList(int fromIndex, int toIndex) {
jaroslav@557:         return (this instanceof RandomAccess ?
jaroslav@557:                 new RandomAccessSubList<>(this, fromIndex, toIndex) :
jaroslav@557:                 new SubList<>(this, fromIndex, toIndex));
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     // Comparison and hashing
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * Compares the specified object with this list for equality.  Returns
jaroslav@557:      * {@code true} if and only if the specified object is also a list, both
jaroslav@557:      * lists have the same size, and all corresponding pairs of elements in
jaroslav@557:      * the two lists are <i>equal</i>.  (Two elements {@code e1} and
jaroslav@557:      * {@code e2} are <i>equal</i> if {@code (e1==null ? e2==null :
jaroslav@557:      * e1.equals(e2))}.)  In other words, two lists are defined to be
jaroslav@557:      * equal if they contain the same elements in the same order.<p>
jaroslav@557:      *
jaroslav@557:      * This implementation first checks if the specified object is this
jaroslav@557:      * list. If so, it returns {@code true}; if not, it checks if the
jaroslav@557:      * specified object is a list. If not, it returns {@code false}; if so,
jaroslav@557:      * it iterates over both lists, comparing corresponding pairs of elements.
jaroslav@557:      * If any comparison returns {@code false}, this method returns
jaroslav@557:      * {@code false}.  If either iterator runs out of elements before the
jaroslav@557:      * other it returns {@code false} (as the lists are of unequal length);
jaroslav@557:      * otherwise it returns {@code true} when the iterations complete.
jaroslav@557:      *
jaroslav@557:      * @param o the object to be compared for equality with this list
jaroslav@557:      * @return {@code true} if the specified object is equal to this list
jaroslav@557:      */
jaroslav@557:     public boolean equals(Object o) {
jaroslav@557:         if (o == this)
jaroslav@557:             return true;
jaroslav@557:         if (!(o instanceof List))
jaroslav@557:             return false;
jaroslav@557: 
jaroslav@557:         ListIterator<E> e1 = listIterator();
jaroslav@557:         ListIterator e2 = ((List) o).listIterator();
jaroslav@557:         while (e1.hasNext() && e2.hasNext()) {
jaroslav@557:             E o1 = e1.next();
jaroslav@557:             Object o2 = e2.next();
jaroslav@557:             if (!(o1==null ? o2==null : o1.equals(o2)))
jaroslav@557:                 return false;
jaroslav@557:         }
jaroslav@557:         return !(e1.hasNext() || e2.hasNext());
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * Returns the hash code value for this list.
jaroslav@557:      *
jaroslav@557:      * <p>This implementation uses exactly the code that is used to define the
jaroslav@557:      * list hash function in the documentation for the {@link List#hashCode}
jaroslav@557:      * method.
jaroslav@557:      *
jaroslav@557:      * @return the hash code value for this list
jaroslav@557:      */
jaroslav@557:     public int hashCode() {
jaroslav@557:         int hashCode = 1;
jaroslav@557:         for (E e : this)
jaroslav@557:             hashCode = 31*hashCode + (e==null ? 0 : e.hashCode());
jaroslav@557:         return hashCode;
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * Removes from this list all of the elements whose index is between
jaroslav@557:      * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive.
jaroslav@557:      * Shifts any succeeding elements to the left (reduces their index).
jaroslav@557:      * This call shortens the list by {@code (toIndex - fromIndex)} elements.
jaroslav@557:      * (If {@code toIndex==fromIndex}, this operation has no effect.)
jaroslav@557:      *
jaroslav@557:      * <p>This method is called by the {@code clear} operation on this list
jaroslav@557:      * and its subLists.  Overriding this method to take advantage of
jaroslav@557:      * the internals of the list implementation can <i>substantially</i>
jaroslav@557:      * improve the performance of the {@code clear} operation on this list
jaroslav@557:      * and its subLists.
jaroslav@557:      *
jaroslav@557:      * <p>This implementation gets a list iterator positioned before
jaroslav@557:      * {@code fromIndex}, and repeatedly calls {@code ListIterator.next}
jaroslav@557:      * followed by {@code ListIterator.remove} until the entire range has
jaroslav@557:      * been removed.  <b>Note: if {@code ListIterator.remove} requires linear
jaroslav@557:      * time, this implementation requires quadratic time.</b>
jaroslav@557:      *
jaroslav@557:      * @param fromIndex index of first element to be removed
jaroslav@557:      * @param toIndex index after last element to be removed
jaroslav@557:      */
jaroslav@557:     protected void removeRange(int fromIndex, int toIndex) {
jaroslav@557:         ListIterator<E> it = listIterator(fromIndex);
jaroslav@557:         for (int i=0, n=toIndex-fromIndex; i<n; i++) {
jaroslav@557:             it.next();
jaroslav@557:             it.remove();
jaroslav@557:         }
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * The number of times this list has been <i>structurally modified</i>.
jaroslav@557:      * Structural modifications are those that change the size of the
jaroslav@557:      * list, or otherwise perturb it in such a fashion that iterations in
jaroslav@557:      * progress may yield incorrect results.
jaroslav@557:      *
jaroslav@557:      * <p>This field is used by the iterator and list iterator implementation
jaroslav@557:      * returned by the {@code iterator} and {@code listIterator} methods.
jaroslav@557:      * If the value of this field changes unexpectedly, the iterator (or list
jaroslav@557:      * iterator) will throw a {@code ConcurrentModificationException} in
jaroslav@557:      * response to the {@code next}, {@code remove}, {@code previous},
jaroslav@557:      * {@code set} or {@code add} operations.  This provides
jaroslav@557:      * <i>fail-fast</i> behavior, rather than non-deterministic behavior in
jaroslav@557:      * the face of concurrent modification during iteration.
jaroslav@557:      *
jaroslav@557:      * <p><b>Use of this field by subclasses is optional.</b> If a subclass
jaroslav@557:      * wishes to provide fail-fast iterators (and list iterators), then it
jaroslav@557:      * merely has to increment this field in its {@code add(int, E)} and
jaroslav@557:      * {@code remove(int)} methods (and any other methods that it overrides
jaroslav@557:      * that result in structural modifications to the list).  A single call to
jaroslav@557:      * {@code add(int, E)} or {@code remove(int)} must add no more than
jaroslav@557:      * one to this field, or the iterators (and list iterators) will throw
jaroslav@557:      * bogus {@code ConcurrentModificationExceptions}.  If an implementation
jaroslav@557:      * does not wish to provide fail-fast iterators, this field may be
jaroslav@557:      * ignored.
jaroslav@557:      */
jaroslav@557:     protected transient int modCount = 0;
jaroslav@557: 
jaroslav@557:     private void rangeCheckForAdd(int index) {
jaroslav@557:         if (index < 0 || index > size())
jaroslav@557:             throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     private String outOfBoundsMsg(int index) {
jaroslav@557:         return "Index: "+index+", Size: "+size();
jaroslav@557:     }
jaroslav@557: }
jaroslav@557: 
jaroslav@557: class SubList<E> extends AbstractList<E> {
jaroslav@557:     private final AbstractList<E> l;
jaroslav@557:     private final int offset;
jaroslav@557:     private int size;
jaroslav@557: 
jaroslav@557:     SubList(AbstractList<E> list, int fromIndex, int toIndex) {
jaroslav@557:         if (fromIndex < 0)
jaroslav@557:             throw new IndexOutOfBoundsException("fromIndex = " + fromIndex);
jaroslav@557:         if (toIndex > list.size())
jaroslav@557:             throw new IndexOutOfBoundsException("toIndex = " + toIndex);
jaroslav@557:         if (fromIndex > toIndex)
jaroslav@557:             throw new IllegalArgumentException("fromIndex(" + fromIndex +
jaroslav@557:                                                ") > toIndex(" + toIndex + ")");
jaroslav@557:         l = list;
jaroslav@557:         offset = fromIndex;
jaroslav@557:         size = toIndex - fromIndex;
jaroslav@557:         this.modCount = l.modCount;
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     public E set(int index, E element) {
jaroslav@557:         rangeCheck(index);
jaroslav@557:         checkForComodification();
jaroslav@557:         return l.set(index+offset, element);
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     public E get(int index) {
jaroslav@557:         rangeCheck(index);
jaroslav@557:         checkForComodification();
jaroslav@557:         return l.get(index+offset);
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     public int size() {
jaroslav@557:         checkForComodification();
jaroslav@557:         return size;
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     public void add(int index, E element) {
jaroslav@557:         rangeCheckForAdd(index);
jaroslav@557:         checkForComodification();
jaroslav@557:         l.add(index+offset, element);
jaroslav@557:         this.modCount = l.modCount;
jaroslav@557:         size++;
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     public E remove(int index) {
jaroslav@557:         rangeCheck(index);
jaroslav@557:         checkForComodification();
jaroslav@557:         E result = l.remove(index+offset);
jaroslav@557:         this.modCount = l.modCount;
jaroslav@557:         size--;
jaroslav@557:         return result;
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     protected void removeRange(int fromIndex, int toIndex) {
jaroslav@557:         checkForComodification();
jaroslav@557:         l.removeRange(fromIndex+offset, toIndex+offset);
jaroslav@557:         this.modCount = l.modCount;
jaroslav@557:         size -= (toIndex-fromIndex);
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     public boolean addAll(Collection<? extends E> c) {
jaroslav@557:         return addAll(size, c);
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     public boolean addAll(int index, Collection<? extends E> c) {
jaroslav@557:         rangeCheckForAdd(index);
jaroslav@557:         int cSize = c.size();
jaroslav@557:         if (cSize==0)
jaroslav@557:             return false;
jaroslav@557: 
jaroslav@557:         checkForComodification();
jaroslav@557:         l.addAll(offset+index, c);
jaroslav@557:         this.modCount = l.modCount;
jaroslav@557:         size += cSize;
jaroslav@557:         return true;
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     public Iterator<E> iterator() {
jaroslav@557:         return listIterator();
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     public ListIterator<E> listIterator(final int index) {
jaroslav@557:         checkForComodification();
jaroslav@557:         rangeCheckForAdd(index);
jaroslav@557: 
jaroslav@557:         return new ListIterator<E>() {
jaroslav@557:             private final ListIterator<E> i = l.listIterator(index+offset);
jaroslav@557: 
jaroslav@557:             public boolean hasNext() {
jaroslav@557:                 return nextIndex() < size;
jaroslav@557:             }
jaroslav@557: 
jaroslav@557:             public E next() {
jaroslav@557:                 if (hasNext())
jaroslav@557:                     return i.next();
jaroslav@557:                 else
jaroslav@557:                     throw new NoSuchElementException();
jaroslav@557:             }
jaroslav@557: 
jaroslav@557:             public boolean hasPrevious() {
jaroslav@557:                 return previousIndex() >= 0;
jaroslav@557:             }
jaroslav@557: 
jaroslav@557:             public E previous() {
jaroslav@557:                 if (hasPrevious())
jaroslav@557:                     return i.previous();
jaroslav@557:                 else
jaroslav@557:                     throw new NoSuchElementException();
jaroslav@557:             }
jaroslav@557: 
jaroslav@557:             public int nextIndex() {
jaroslav@557:                 return i.nextIndex() - offset;
jaroslav@557:             }
jaroslav@557: 
jaroslav@557:             public int previousIndex() {
jaroslav@557:                 return i.previousIndex() - offset;
jaroslav@557:             }
jaroslav@557: 
jaroslav@557:             public void remove() {
jaroslav@557:                 i.remove();
jaroslav@557:                 SubList.this.modCount = l.modCount;
jaroslav@557:                 size--;
jaroslav@557:             }
jaroslav@557: 
jaroslav@557:             public void set(E e) {
jaroslav@557:                 i.set(e);
jaroslav@557:             }
jaroslav@557: 
jaroslav@557:             public void add(E e) {
jaroslav@557:                 i.add(e);
jaroslav@557:                 SubList.this.modCount = l.modCount;
jaroslav@557:                 size++;
jaroslav@557:             }
jaroslav@557:         };
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     public List<E> subList(int fromIndex, int toIndex) {
jaroslav@557:         return new SubList<>(this, fromIndex, toIndex);
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     private void rangeCheck(int index) {
jaroslav@557:         if (index < 0 || index >= size)
jaroslav@557:             throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     private void rangeCheckForAdd(int index) {
jaroslav@557:         if (index < 0 || index > size)
jaroslav@557:             throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     private String outOfBoundsMsg(int index) {
jaroslav@557:         return "Index: "+index+", Size: "+size;
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     private void checkForComodification() {
jaroslav@557:         if (this.modCount != l.modCount)
jaroslav@557:             throw new ConcurrentModificationException();
jaroslav@557:     }
jaroslav@557: }
jaroslav@557: 
jaroslav@557: class RandomAccessSubList<E> extends SubList<E> implements RandomAccess {
jaroslav@557:     RandomAccessSubList(AbstractList<E> list, int fromIndex, int toIndex) {
jaroslav@557:         super(list, fromIndex, toIndex);
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     public List<E> subList(int fromIndex, int toIndex) {
jaroslav@557:         return new RandomAccessSubList<>(this, fromIndex, toIndex);
jaroslav@557:     }
jaroslav@557: }